The invention relates to a structured packing for producing intimate contact of fluids, for example liquid-liquid, liquid-gas, or gas-gas, particularly in a mass and/or heat exchange apparatus. More particularly, the invention relates to a structured packing assembly for enhancing contact between a first fluid having a predominantly downward direction of flow, and a second fluid, the packing having a plurality of juxtaposed sheets.
Structured packings in general have a well-defined geometry of discrete flow channels facilitating theoretical estimation of the performance of the transfer device. Structured packings of various designs have been known in the chemical industry for decades. They are generally known to offer a lower resistance to flow than bulk (random) packing, and lend themselves to easy installation within a mass exchange chamber. Structured packing elements may be constructed of corrugated of fluted plates, such as known e.g., from U.S. Pat. Nos. 4,929,399 to Lockett et al.; 5,407,607 to Mix; 5,188,773 to Chen et al; 5,624,733 to McKeigue et al. and 5,132,056 to Lockett et al.
In most of the prior art solutions, the corrugations, folds or flutings are arranged at an angle to the vertical, or the axis of the column or tower. This has the effect of non-uniform distribution of the liquid flow over the surface of the packing plates.
U.S. Pat. No. 2,042,127 to Sayles describes a structured packing assembly composed of a number of generally vertically disposed, parallel, generally flat sheets arranged in superimposed tiers. The assembly features collectors disposed at the top of a tier for distribution of down-flowing liquid over both sides of the subjacent plates. It is noted that Sayles advocates the sheets being disposed as close as possible to prevent cascading, or free-fall of liquid through the packing.
While the parallel-sheet concept of Sayles is useful, there is still a need in the mass/energy transfer industry for a simple, low weight (low material cost) structured packing and a large surface area (high efficiency interphase transfer) with a relatively low pressure drop. It is also very important that vapour and liquid be able to transfer between sheets so that uniform liquid and vapour distribution over the column or tower cross-section be maintained. The uniform distribution of fluids is essential for achieving high efficiency of mass transfer. The ease of assembly and placement in the exchange apparatus (e.g., a tower) as well as the structural quality of the packing are also of importance.